The present invention is a composition of a method for use as a corrosion inhibited, freeze protected, heat transfer fluid. More particularly, the composition is a polyhydroxy alcohol-based, especially ethylene glycol-based, antifreeze composition which is designed to protect internal combustion engines and other devices from corrosion. A preferred use of the composition of the present invention is in applications wherein freeze protection is desired but there is no mechanical circulation of the heat transfer fluid.
Generally, water is the accepted heat exchange medium for the circulating cooling systems of internal combustion engines. It is also widely used as the heat transfer medium in non-circulating systems such as natural gas heaters which are used to prevent freezing of moisture in natural gas pipelines. The heater is a large right cylndrical vessel typically two to three feet in diameter with a tube inside which has a flame. Also inside are tubes which carry the moist gas which is to be heated. The vessel is filled with the heat transfer fluid. The main corrosion problem in such applications is the corrosion of the ferrous metals from which the vessel and the tubes are made.
Ethylene glycol is the polyhydroxy alcohol which is widely used to lower the freezing point of water and to raise its boiling point to enable the heat exchange medium to be used over a wider range of temperatures. Ethylene glycol and other such antifreezes tend to corrode the metals from which engines and heaters are made. Therefore, it has been necessary to add corrosion inhibitor compositions to the antifreeze solutions to lessen the corrosive effect of the solutions. British Pat. No. 1,210,370 discloses an antifreeze composition for use as the heat exchange medium for the cooling system of an internal combustion engine. This composition is comprised of a water soluble alcohol, an alkali metal nitrate, an alkali metal borate, a phosphate, a heterocyclic benzo-compound, and, optionally, an alkali metal nitrite. This composition differs from the composition of the present invention in that in the present invention, borate is not necessary and nitrate is to be avoided.